The previous Red List assessments for Galápagos tortoises treated the various allopatric island populations as subspecies of Chelonoidis nigra, as did several authors (Pritchard 1996; Caccone et al. 1999; Beheregaray et al. 2003; Fritz and Havas 2007; TTWG 2007, Rhodin et al. 2008). However, other authors have considered them as full species based on morphology (Bour 1980; Fritts 1983; Ernst and Barbour 1989) and more recently several researchers (Caccone et al. 2002; Russello et al. 2005, 2007; Poulakakis et al. 2008, 2012, 2015; Chiari et al. 2009) have treated most of them as full species based on congruent patterns of mitochondrial and nuclear variation. This elevated species-level taxonomy has been largely accepted by TTWG (2009, 2014) and TEWG (2015) for most phylogenetic lineages of Galápagos tortoises. This Red List assessment therefore now treats C. abingdonii as a full species, rather than retaining its previous subspecies ranking from earlier Red List assessments.

The name Testudoephippium, athough widely applied to the Pinzón [Duncan Island] Tortoise in the past, was interpreted by Pritchard (1996) to possibly be based on a type specimen from Pinta, and therefore potentially a senior synonym of Testudo abingdonii, but this has not yet been determined genetically.

Justification:
With the death of the last known Pinta Tortoise, Lonesome George (in captivity since 1972), on 24 June 2012, the species went extinct. Extensive surveys have failed to find other tortoises on Pinta or in any of the world’s zoos. Tortoises with up to 50% abingdonii genes have been reported from Volcán Wolf on northern Isabela, including first generation hybrids, but no pure individuals of abingdonii are known to exist (TEWG, 2015). This assessment incorporates contributions from the international workshop on Galápagos tortoises convened by the Galápagos National Park Directorate in July 2012.

Chelonoidis abingdonii occurred on Pinta [formerly Abingdon Island] in the Galápagos Islands of Ecuador. Pinta has a total surface area of 59.4 sq.km, of which 24.5 sq. km / 41% could potentially sustain tortoises (Gibbs, unpubl. data).

Based on an estimated average density of one tortoise per hectare of suitable habitat, the pre-impact population was estimated to have been about 2,500 adults (Gibbs, unpubl. data). The Pinta Giant Tortoise was heavily exploited and its population collapsed in the middle of the 19th century, followed by significant collecting in the late 19th and early 20th centuries and exploitation by local fishermen subsequently. The last surviving animal, Lonesome George, was collected from the wild in 1972 and transferred to the Government of Ecuador’s Tortoise Centre on Santa Cruz, where he died on 24 June 2012. No further animals have been found on Pinta despite extensive surveys (Pritchard 1996). During the final goat eradication project (1998-2003), park ranger activity covered the island and yielded no sign of tortoises. In 2008, the Galápagos National Park Directorate carried out the last massive search for tortoises, but only found a few tortoise shells at the bottom of crevices (Cayot 2014).

Chelonoidis abingdonii was a saddlebacked tortoise adapted for browsing on higher vegetation, in particular, low-hanging cactus pads. Pinta habitat, before its destruction by feral goats, was largely dry xeric brushland and grassland at lower elevations, with limited more mesic forest habitat at higher elevations. Opuntia cactus trees are dominant in much of the Arid and Transition Zones on the island and provide an important food resource for tortoises. Habitats are now recovering following goat eradication.

Legislation and regulations: Chelonoidis abingdonii is protected under Ecuadorian national law. It has been included in Appendix I of CITES since 1975, prohibiting all forms of commercial international trade. The entirety of Pinta Island, and therefore 100% of this species’ native range, is protected as part of the Galapagos National Park.

Captive breeding attempts with Lonesome George, the last known individual of C. abingdonii, were undertaken off and on during the 40 years of his residence at the Government of Ecuador’s Tortoise Centre on Santa Cruz, but he never reproduced. Goats were eradicated from Pinta in 1999 (Campbell et al. 2004). Ecosystem restoration on Pinta needs to continue to secure its other biodiversity. For that reason in May 2010, thirty-nine sterilized adult tortoises of various hybrid origins were released on to Pinta to act as non-reproductive natural ecosystem engineers to initiate a more natural habitat restoration process (Hunter et al. 2013). An ongoing project to remove hybrid tortoises with partial Pinta ancestry from Volcán Wolf on Isabela to begin a captive breeding programme is underway. Their reproductive offspring will be released on to Pinta, followed by long-term monitoring of the population.